Method of making tappets



May 23, 1933. J. H. HOERN METHOD OF MAKING TAPPET S Filed June 14, 1930 VEW TOR JOSEPHH 1101mm W flTTO/P/VEY Patented May 23, 1933 JOSEPH H. HOERN, OF SAGINAW, MICHIGAN,

ASSIGNOR TO WILCOX-RIG'H CORPORATION,

OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN METHOD OF MAKING TAPPETS Application filed June 14,

This invention relates to valve tappets and their method of manufacture.

Heretofore in the manufacture of tappets for internal combustion engines, especially tappets that require to be light on account of their use in high speed engines, it has been customary to first make a one-piece tappet by cutting the stem and head from a bar of steel, then to make the stem tubular by boring a hole through it lengthwise so as to leave only a thin wall or tubular stem. The tubular stem was then plugged at the head end of the tappet by a tightly fitting steel plug and finally the working face of the tappet head was built up by puddling cast iron in a thin layer over the working face of the tappet and over the inserted steel plug.

My invention relates to tappets of this general character, and the improvement is found in a novel method and structure whereby I have overcome certain disadvantages that were inherent in the above described earlier method. One of the inherent disadvantages referred to was that after the tight-fitting steel plug had been inserted in the tubular stem and the cast iron face was being puddled into place gases were liberated at the joint between the steel plug and the wall of the tappet bore, and these gases escaped through the metal that was being puddled, so that imperfections were frequently found in the structure of the puddled iron tappet face around the periphery of the steel plug. This resulted in an undesirable proportion of rejects. The object of my present invention, as already stated, is to overcome this defect and to produce a tappet of the same general construction and characteristics as were produced by the former method but to avoid the disadvantages above mentioned that necessarily included the use of such a plug.

The means by which I attain the abovementioned objects and the method of procedure in its manufacture will now be explained.

In the drawing Fig. 1 is a longitudinal sectional view of a tappet embodying my improvement.

Fig. 2 is a face view of the same.

Numeral 1 indicates the tubular thin walled 1930. Serial No. 461,234.

tappet stem and 2 is a mushroom head integral. with the stem, the face of the head being preferably recessed, as at 3, to provide a receptable for the mass of puddled metal that constitutes the working face of the tappet.

My invention provides the plug for the end of the tubular stem 1 in the following manner A slug 4 of metal of any suitable form and length is fixed into the bore of the tubular stem 1 near its head end and is held there by press fit or otherwise. The cavity 5 thus formed at the end of the tubular stem is then filled with a button-like mass 8 of puddled metal, preferably mild steel. The hot metal becomes welded to the walls of the cavity 5 and to the face of the slug 4 and the cavity is filled up practically flush with the surface of the tappet head 2. Finally metal such as cast iron is added, by puddling, to the face 2a of the tappet head 2 so as to cover it and also to cover the end of the button 6 of puddled metal. I

It has been found in practice that the but ton 6 having been fused or puddled into place and backed by the slug 4 avoids the formation of gas when the metal working face element 7of the tappet is thereafter puddled into place. No gases can arise from between the plug and the wall of the stem, as in the earlier structures referred to and consequently the puddled iron working face 7 is without the defects which were heretofore frequently found in a face which was puddled in place directly upon a metal plug which was inserted in the stem as a backing.

By the means above described I have provided a simple and inexpensive method of applying a cast iron puddled face to the head of a thin walled tubular tappet and am enabled to secure uniformly satisfactoryresults, so that the present method is well adapted for the manufacture in mass production of tappets of the kind described.

Having thus described my invention, what I claim and desire to secure by Letters Pat-' cut is:

' The method of applying to a tubular tappet stem a face element devoid of imperfections comprising fixing a slug of metal in the bore of the stem near an end thereof to present a cavity Within the stem, depositing on said slug Within the cavity a mass of fused metal and Welding the same to the sing and t0 the Walls of the stem, so as to seal said slug gas-tight to the stem, and thereafter applying to the said deposited mass an additional quantity of fused metal and shaping the same to form said face element.

In testimony whereof, I aflix my signature.

JOSEPH H. HOERN. 

